Flotation machine

ABSTRACT

1. A FROTH APPARATUS COMPRISING SIDE AND BOTTOM WALL MEANS DIFINING A CELL FOR HOLDING A FLOTATION LIQUID TO BE TREATED, FEED MEANS FOR FEEDING SAID LIQUID INTO SAID CELL, DISCHARGE MEANS FOR DISCHARGING SAID LIQUID FROM THE CELL AFTER SAID LIQUID HAS BEEN SUBJECTED TO FLOTATION THEREIN, FROTH REMOVAL MEANS AT THE UPPER END OF THE CELL FOR DISCHARGING FROTH FROM THE CELL, AN UPRIGHT IMPELLER SHAFT EXTENDING DOWNWARDLY INTO THE CELL FOR CIRCULATING THE FLOTATION LIQUID AROUND THE CIRCUMFERENCE OF THE CELL, AND MEANS FOR SUPPLYING GAS INTO SAID CELL IN THE VICINITY OF SAID IMPELLER SHAFT FOR MIXING THE GAS WITH THE FLOTATION LIQUID TO GENERATE IN THE CELL A FROTH ENRICHED WITH A SELECTED COMPONENT OF SAID FLOTATION LIQUID, WHICH FROTH RISES TO THE SURFACE OF THE LIQUID AND IS DISCHARGED FROM THE CELL BY SAID FROTH REMOVAL MEANS, WHEREIN THE IMPROVEMENT COMPRISES: SAID REED MEANS IS A FEED OPENING IN THE SIDE WALL OF THE CELL, DISPOSED CLOSE OF THE BOTTOM WALL THEREOF AND OPENING INTO THE CELL IS A DIRECTION SUBSTANTIALLY TANGENTIAL TO THE DIRECTION OF MOVEMENT OF THE FLOTATION LIQUID IN THE CELL; AND SAID DISCHARGE MEANS IS A DISCHARGE OPENING IN THE SIDE WALL OF THE CELL AT A LOCATION CIRCIMFERENTIALLY SPACED FROM SAID FEED OPENING AND OPENING INTO THE CELL IN A DIRECTION SUBSTANTIALLY TANGENTIAL TO THE DIRECTION OR MOVEMENT OF THE FLOTATION LIQUID IN THE CELL, SAID DISCHARGE OPENING BEING LOCATED ON SAID SIDE WALL AT A POSITION NOT HIGHER THAN THE POSITION OF SAID FEED OPENING.

Oct. 15, 1974 FIG. I

Filed Jan. 16, 1973 1974 TATSUYA NA'GAHAMA 3,842,004

FLOTA'I'ION macaw: I

COMPARISON FLOTATION MACHINE v 2 Shets-Sheet 3 United States Patent 3,842,004 FLOTATION MACHINE Tatsuya Nagahama, Tokyo, Japan, assignor to Mitsui Mining & Smelting Co., Ltd., Chno-ku, Tokyo, Japan Filed Jan. 16, 1973, Ser. No. 324,199 Claims priority, application Japan, Jan. 22, 1972, 47/ 8,432 Int. Cl. B0311 1/00 US. Cl. 210-44 9 Claims ABSTRACT OF THE DISCLOSURE A flotation machine comprising at least one flotation cell wherein the liquid for flotation moves in a circumferential direction along the side wall thereof. The flotation cell is provided on its side wall with one opening to feed the liquid for flotation and one opening to discharge the liquid for flotation. The discharge opening is disposed on said side wall at a vertical position level with or lower than the feed opening. Both of the feed and discharge openings open in a tangential direction, or in an approximately tangential direction, relative to the direction of movement of the liquid for flotation.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a flotation machine.

Description of the prior art In the prior art, there was employed a flotation machine consisting of plural flotation cells connected in series as shown in FIG. 1 of the appended drawings. In FIG. 1, the numerals 1, 1' and 1 denote three flotation cells connected in serial arrangement. In cell 1, there is provided the impeller shaft 2, the stand pipe 3, the side wall 4, the flotation liquid feed opening 5, the flotation liquid discharge opening 6 and the froth-discharging trough 7. It will be understood that the cells 1' and 1" are constructed similarly. In such conventional flotation machines, the means for connecting one flotation cell with the next flotation cell varies with the type of flotation machine. In the cases of the Warman flotation machine and the Agitair flotation machine, there is provided practically no partition wall between the flotation cells. The flotation cells are connected with one another either by means of the side walls of the flotation cells or by means of a part of their common side wall. In the case of the Denver Type Sub-A Flotator, each flotation cell is provided with a damper or baflle, whereby the flotation liquid overflowing said damper is supposed to be sucked by an impeller through a suction pipe of the next flotation cell. However, all of these conventional flotation machines suffer from the phenomenon of the flotation liquid short-circuiting. This short-circuiting phenomenon is especially conspicuous in the case of a flotation machine devised to rotate the flotation liquid within its flotation cells, so that here has been a demand for means for preventing said shortcircuiting in flotation machines of this type.

SUMMARY OF THE INVENTION The present invention is intended to provide a flotation machine which meets the foregoing demand. According to the invention there is provided a flotation machine devised to move the flotation liquid in a circumferential direction within its flotation cells. Each cell is provided in its side wall with an opening to feed the flotation liquid in a tangential or approximately tangential direction relative to the direction of the flow of the flotation liquid within the flotation cells, and an opening to discharge the flotation liquid after completion of the flotation in another Patented Oct. 15, 1974 tangential or approximately tangential direction relative to the direction of the flow of the flotation liquid within the flotation cells. The discharge opening is disposed at a vertical position level with or lower than said feed opening.

Further particulars of the present invention will be described in the following by reference to the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the appended drawings, FIG. 1 is a plan view of a conventional flotation machine consisting of a plural number of flotation cells connected in series, FIG. 2 is a plan view of a flotation machine embodying the present invention, FIG. 3 is a side view of the same flotation machine illustrated in FIG. 2, FIG. 4 is a side view of a modified flotation machine embodying the present invention, FIG. 5 is a plan view -of still another flotation machine embodying the present invention, and FIG. 6 is a plan view of a flotation machine employed for the purpose of comparative tests.

DETAILED DESCRIPTION OF THE INVENTION Referring to the flotation machine i lustrated in FIGS. 2 and 3, the numbers 21, 21' and 21" denote flotation cells connected in serial arrangement. The cells are constructed alike and each includes an impeller shaft 22, a stand pipe 23, a side wall 24, a flotation liquid feeding opening 25, a flotation liquid discharge opening 26, a froth-discharging trough 27, and a connecting pipe 28. The arrows show the direction of flow of the flotation liquid. The flotation liquid within the connecting pipes 28 is fed into each of the flotation cells through the feeding openings 25 which open in a direction approximately tangential to the flow of the liquid within each flotation cell. The flotation liquid is fed through the cells in succession and, in each cell, said liquid moves circumferentially therein. The flotation is carried out during this circumferential movement. Upon completion of the flotation within each flotation cell, the flotation liquid is discharged through the outlet 26, which is disposed at a vertical level lower than the feeding opening 25, into the connecting pipe 28, the discharged liquid flowing in a substantially tangential direction relative to the flow within the flotation cell.

Inasmuch as the flotation liquid is caused to move within the flotation cells (21, 21 and 21") and the connecting pipes 28 as stated above, there does not occur the phenomenon of short-circuiting. There is obtained flotation efliciency superior to the efficiency of conventional flotation machines.

FIG. 4 illustrates another flotation machine embodying the present invention, wherein the flotation cells are connected in series with each cell being vertically lower than the preceding cell in the series. A flotation machine of this type is advantageous when the flowing quantity of the flotation liquid per unit time is high. In FIG. 4, the numbers 31, 31 and 31" denote the flotation cells in serial arrangement, 32 denotes the impeller shaft, 34 denotes the side wall of the flotation cell, 35 denotes the flotation liquid feeding opening, 36 denotes the flotation liquid discharging opening and 38 and 38' denote the connecting pipes respectively.

The reason for disposing the flotation liquid discharge openings at a vertical position lower than or level with the flotation liquid feeding opening, in the present invention, is that such a disposition will render the contact between the flotation liquid and the bubbles within the flotation cell more frequent than the case of disposing the discharge opening higher than the feed opening. This disposition enhances greatly the flotation efficiency.

In this connection, the lateral spacing of the discharging opening and feeding opening in the present invention is not critical, but, in the embodiment shown in FIG. 3, where the flotation liquid moves from right to left within the connecting pipes 28, it is preferable that the discharge opening 26 be disposed to the right of and laterally spaced from opening 25. By so doing, the risk that the flotation liquid fed to the flotation cell will be discharged prior to its full movement within said cell can be minimized. The same effect can be obtained from application of the present invention to a square-shaped flotation cell, as shown in FIG. 5, as well as to a round flotation cell, as shown in FIGS. 2 and 3. In FIG. 5, the numbers 41, 41 and 41" denote the flotation cells connected in serial arrangement, 42 denotes the impeller shaft, 43 denotes the stand pipe, 44 denotes the side Wall of the flotation cell, 45 denotes the flotation liquid feeding opening and 46 denotes the flotation liquid discharge opening.

A flotation machine according to the present invention has the advantages that, not only is the occurrence of the phenomenon of the flotation liquid short-circuiting prevented, resulting in an enhancement of the flotation efficiency as discussed in the foregoing, but also the power necessary for driving the flotation machine can be minimized inasmuch as the direction of feeding and discharging the flotation liquid is identical with the direction of its movement within the flotation cell.

Hereunder will be given examples of comparative flotation tests to show the differences in the results obtained by (l) flotation performed by employing a flotation machine according to the present invention as shown in FIGS. 2 and 3 and (2) flotation performed by employing a comparative flotation machine provided with flotation cells of the same size as that of the present machine, said cells being connected with one another and equipped with feeding openings and discharging openings aligned in the radial direction as shown in FIG. 6.

In FIG. 6, the numbers 51, 51 and 51" denote the flotation cells connected in serial arrangement, 52 denotes the impeller shaft, 53 denotes the stand pipe, 54 denotes the side wall of flotation cell, and 57 denotes the frothdischarging trough.

Test 1 This example is illustrative of flotation of ions. That is, flotation was effected by adding sodium ethyl xanthate and a frother to an industrial waste water having a Cu++ concentration of 30 ppm. to form precipitates of Cu xanthate. The results were as shown in the following table.

This example is illustrative of flotation by precipitation. That is, flotation was effected by adding sodium sulfide to an industrial waste water having Cd++ concentration of 2 ppm. to form precipitates of CdS, and then adding sodium ethyl xanthate and a frother. The results were as shown in the following table.

Cd concentra- Distribution ratio of tion in tail- Cd (percent) ings after flotation Tailings Froth Performance (p.p.m.)

Flotation machine:

Flotation machine according to the present invention 0. 01 0. 99. 5 Comparative flotation machine 0. O8 4. 0 96. O

4 Test 3 This example is illustrative of flotation of fine particles. That is, flotation was effected by adding sodium ethyl xanthate and a frother to an industrial waste water containing zinc blend particles of less than 10g in particle size in an amount of 200 p.p.m. in terms of Zn concentration. The results were as shown in the following table.

Zn concentration in Distribution ratio railings after of Zn (percent) flotation Performance (p.p.m.) Tailings Froth Flotation machine:

Flotation machine according to present invention 3. 5 1. 7 98. 3 Comparative flotation machine. 9.0 4. 5 95. 5

Test 4 This example is illustrative of flotation of ores. That is, a zinc ore having a zinc content of 4.5% was crushed into grains comprising 18% by weight of grains having a grain size of -65 mesh, and then a pulp having 40% concentration of said grains was prepared. -By adding copper sulfate, sodium ethyl xanthate and a frother to this pulp, flotation was effected. The results were as shown in the following table.

Distribution ratio Amount of Zn of Zn (percent) in tailings (percent) Floating Performance"; Tailings ore Flotation machine:

Flotation machine according to the present invention 0. 08 2. 0 98. 0 Comparative flotation machine 0. 20 5. 0 95. 0

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A froth apparatus comprising side and bottom Wall means defining a cell for holding a flotation liquid to be treated, feed means for feeding said liquid into said cell, discharge means for discharging said liquid from the cell after said liquid has been subjected to flotation therein, froth removal means at the upper end of the cell for discharging froth from the cell, an upright impeller shaft extending downwardly into the cell for circulating the flotation liquid around the circumference of the cell, and means for supplying gas into said cell in the vicinity of said impeller shaft for mixing the gas with the flotation liquid to generate in the cell a froth enriched with a selected component of said flotation liquid, which froth rises to the surface of the liquid and is discharged from the cell by said froth removal means, wherein the improvement comprises: said feed means is a feed opening in the side wall of the cell, disposed close to the bottom wall thereof and opening into the cell in a direction substantially tangential to the direction of movement of the flotation liquid in the cell; and

said discharge means is a discharge opening in the side wall of the cell at a location circumferentially spaced from said feed opening and opening into the cell in a direction substantially tangential to the direction of movement of the flotation liquid in the cell, said discharge opening being located on said side wall at a position not higher than the position of said feed opening.

2- A froth flotation apparatus according to Claim 1, in which both the feed opening and the discharge opening are disposed in the lower half of the side wall of the cell.

3. A froth flotation apparatus according to Claim 2, in which the discharge opening is laterally spaced from the feed opening so that the included angle defined by imaginary lines drawn from the feed and discharge openings to the center of said cell is less than whereby the flotation liquid flows through an arc of more than V 180 within said cell.

4. A froth flotation apparatus according to Claim 3, in which said included angle is less than about 90 and greater than 0".

5. A froth flotation apparatus according to Claim 1, in which said means for supplying gas comprises a stand pipe surrounding said shaft and said froth removal means is a trough communicating with the upper end of said cell and disposed along the side wall thereof.

6. A froth flotation apparatus according to Claim 1 comprising a plurality of said cells connected in series with the discharge opening of each cell being connected by a conduit to the feed opening of the following cell in the series.

7. A froth flotation apparatus according to Claim 6, in which the cells lie in substantially the same horizontal plane and the conduits connecting adjacent cells in the series are inclined upwardly with respect to the horizontal in the direction of flow of the flotation liquid.

8. A flotation machine according to Claim 6, in which the cells are disposed at progressively lower vertical levels and the conduits connecting adjacent cells in the series are inclined downwardly with respect to the horizontal in the direction of flow of the flotation liquid.

9. In a flotation process in which a feed liquid is fed into a cell and is subjected to flotation therein by mixing same with gas bubbles to form a froth which rises to the top of the cell and is discharged therefrom and the re- 6 mainder of the treated liquid is separately discharged from the cell, so that said froth and the treated liquid respectively have diiferent concentrations of constituents than said feed liquid, the improvement which comprises feeding the feed liquid substantially tangentially into the cell through the side wall thereof, moving the liquid within the cell in a substantially circumferential direction relative to said side wall while said liquid is being subjected to flotation and then discharging the treated liquid through the side wall of the cell in a substantially tangential direction at a vertical position not higher than the position at which the feed liquid is fed into the cell.

References Cited UNITED STATES PATENTS 3,669,883 6/1972 Huckstedt et 'al. 21O44 711,155 10/1902 Gathmann 2l0512 2,425,932 8/1947 Green et a1 210512 FOREIGN PATENTS 1,945,922 4/1971 Germany 210-512 SAMIH N. ZAHARNA, Primary Examiner F. F. CALVETTI, Assistant Examiner US. Cl. X.R.

. UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No. 3 42 004 Dated October 15. 1974 Inventor(s) Tats'uya Nagahama It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column '4 line 39; change "A froth apparatus" to -A froth flotation apparatus--.

Signed and sealed this 14th day of January 1975.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PC9-1 (10-59) USCOMM-DC 60376-P69 U.S. GOVERNMENT PRINTING OFFICE I969 O-333l. 

1. A FROTH APPARATUS COMPRISING SIDE AND BOTTOM WALL MEANS DIFINING A CELL FOR HOLDING A FLOTATION LIQUID TO BE TREATED, FEED MEANS FOR FEEDING SAID LIQUID INTO SAID CELL, DISCHARGE MEANS FOR DISCHARGING SAID LIQUID FROM THE CELL AFTER SAID LIQUID HAS BEEN SUBJECTED TO FLOTATION THEREIN, FROTH REMOVAL MEANS AT THE UPPER END OF THE CELL FOR DISCHARGING FROTH FROM THE CELL, AN UPRIGHT IMPELLER SHAFT EXTENDING DOWNWARDLY INTO THE CELL FOR CIRCULATING THE FLOTATION LIQUID AROUND THE CIRCUMFERENCE OF THE CELL, AND MEANS FOR SUPPLYING GAS INTO SAID CELL IN THE VICINITY OF SAID IMPELLER SHAFT FOR MIXING THE GAS WITH THE FLOTATION LIQUID TO GENERATE IN THE CELL A FROTH ENRICHED WITH A SELECTED COMPONENT OF SAID FLOTATION LIQUID, WHICH FROTH RISES TO THE SURFACE OF THE LIQUID AND IS DISCHARGED FROM THE CELL BY SAID FROTH REMOVAL MEANS, WHEREIN THE IMPROVEMENT COMPRISES: SAID REED MEANS IS A FEED OPENING IN THE SIDE WALL OF THE CELL, DISPOSED CLOSE OF THE BOTTOM WALL THEREOF AND OPENING INTO THE CELL IS A DIRECTION SUBSTANTIALLY TANGENTIAL TO THE DIRECTION OF MOVEMENT OF THE FLOTATION LIQUID IN THE CELL; AND SAID DISCHARGE MEANS IS A DISCHARGE OPENING IN THE SIDE WALL OF THE CELL AT A LOCATION CIRCIMFERENTIALLY SPACED FROM SAID FEED OPENING AND OPENING INTO THE CELL IN A DIRECTION SUBSTANTIALLY TANGENTIAL TO THE DIRECTION OR MOVEMENT OF THE FLOTATION LIQUID IN THE CELL, SAID DISCHARGE OPENING BEING LOCATED ON SAID SIDE WALL AT A POSITION NOT HIGHER THAN THE POSITION OF SAID FEED OPENING. 